Allan b



A. M. MASSER.

GRATE BAR.

APPLICATION men MAY 2|. m2.

Patented Aug. 26, 1919.

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UNITED STATES PATENT OFFICE.

ALLAN M. MASSER, OF CHICAGO, ILLINOIS, ASSIGNOR 'IO COMBUSTION SERVICECORPORATION, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

GRATIS-BAR.

Specification of Letters Patent.

Patented A11 26, 1919.

To all whom it may concern:

Be it known that I, ALLAN M. MAssnn, a citizen of the United States ofAmerica, and a resident of Chicago, county of Cook, and State ofIllinois, have invented certain new and useful Improvements inGrate-Bars, of which the following is a specification.

This invention relates to grate bars, and particularly to those whichare intended for use in coal furnaces having forced draft. Some of theprime requisites of such bars are permanence of form, capability todistribute the supply of air for combustion as uniformly as possiblethroughout the grate area and to preheat the air nearly to the ignitiontemperature in transmitting it to the fuel, and also capability torapidly conduct away excessive heat from the combustio-n surfaces anddistribute such heat to the more remote and downward parts of the gratewhereby it may most efliciently preheat the air and whereby any excessheat may be radiated and suitably disposed of without harm.

Many attempts have heretofore been made to meet these requirementsefficiently, and varying degrees of success have been attained byfitting the bars together in various ways and providing apertures andair passages in, through and between the bars, but the prior devices forone reason or another have been more or less deficient, and moreover theever increasing demands for capacity, space economy, smoke prevention,low initial cost, and inexpensive maintenance and operation continuallydevelop new problems of refinement and efficiency.

WVhen coal is burned the process which occurs consists of two distinctope -ations, which, however, may be continuous and the one immediatelysuccessive with respect to the other. The first operation, whichrequires a comparatively low temperature and is independent of thepresence of air, is one of destructive distillation similar to thatwhich occurs in the retorts of gasworks. It

results in the decomposition of the coal and formation of numeroussubstances including hydrogen and certain hydrocarbon gases, certainnitrogenous compounds, and coke. It is these products of distillation,not the coal itself, that burn, in the strict sense of the word; andthis second operation requires the presence of air and also a muchhigher temperature than the first. If the combustion is perfect theproducts are mainly water-vapor, carbon dioxid, nitrogen, and sulfurdioxid, part of the nitrogen being liberated from the fuel but thegreater part being derived from the air which has supplied the necessaryoxygen.

Two things are necessary for insuring such complete combustion, namelyan adequate but not too large supply of air properly administered, andthe maintenance of the requisite temperature. In practice, however,these conditions are never perfectly fulfilled and consequently thecombustion of coal is always more or less imperfect and gives rise to agreater or less waste of fuel elements, the more important of whichinclude certain hydrocarbons, carbon monoxid, and unburnt carbon in avery finely divided state. This mixture commonly referred to as smokeusually includes considerable volumes of unused air.

The main objects of this invention are to provide an improved and moreeflicient form of g ate, adapted especially for forced draft furnaces;to provide an improved form of grate bar adapted to avoid warping, andhaving apertures better disposed and shaped to economically distributeand discharge the certain requisite supply of air at a propertemperature forcibly and uni-- formly in finely divided streams, welldistributed, so as to effect more even and speedy combustion, and so asto avoid admission and useless heating of more air than required tovsupport complete combustion; to so form and dispose the apertures as toavoid substantial weakening of the bars, and so as to cause upward crosscurrents of air to be discharged obliquely into the fuel in such manneras to more thoroughly equalize the distribution of air throughout thefuel mass and thus permit of supplying a thicker fuel bed such as mayrequire the least amount of attention and may keep free from holesburning through; and to provide downward ribs or flanges on the bars,formed and adapted both to preheat the air and by due 'adiation toprevent warping or fusing of the bars, as well as to reinforce the barsand provide suitable pockets for the collection of a packing of cindorsand ash between bars so as to insure all of the air passing through thebar apertures or perforations.

An illustrative embodiment of this invention is shown in theaccompanying drawings, in which Figure 1 is a fragmentary plan showingadjacent ends of a plurality of the improved grate bars, relativelydisposed as in a grate.

Fig. 2 is a central vertical section running lengthwise through one ofthe bars on the line .AA of Figs. 1 and 2.

Fig. 3 is a cross section through a' group of bars on the line BB ofFig. 1.

In the embodiment shown in the drawings each bar 1 comprises ahorizontal body part 2 having downward flanges 3 on each side and also amedial downward web 1. These flanges and webs constituting substantiallya series of ribs, giving the bar an M-shape, and serve mainly for twoimportant functions, namely to strengthen the bar, which is made aslight as practicable, and to facilitate distribution and radiation ofheat, as well as preheating of the draft air. The strengthening iseffected by the truss-like form of the downward members 3 and 4E, andheat radiation and preheating are efliciently provided for by the broadsurfaces which said flange and web members expose to the air passingthrough the narrow spaces between them.

In order to distribute the air of the forced draft uniformly andefliciently over the whole grate area and to best adapt the grate forinsuring proper combustion, numerous small apertures or air passagesthrough the bars are provided of definite form and particular relationwith respect to each other and to the several parts of the bar, as willbe more fully described. For this purpose each bar is provided withalternate groups of perforations 5 and 6 respectively, said groups assuch being of different character and form, the holes 5 being arrangedin circular form and the holes 6 being arranged in pairs alinedcrosswise of the bars. In each group the holes are disposedsymmetrically on opposite sides of the middle rib or web 4. The holes orjets 5 and 6 are all inclined divergently upward in each group so as toimpart somewhat of radial movement to the air as it is discharged upwardinto the fuel, and the discharge or nozzle end of each hole isconsiderably restricted or narrowed with respect to the intake end andbody of the passage, so as to cause the air to be ejected forcibly wellup into the mass of the fuel.

Each circular group of holes 5 preferably comprises a pair of nearlysemicircular apertures, one on each side of web 4, and the outward flareof each preferably increases somewhat toward the top, as best shown bythe outer bar sections in Fig. 3. The restricted nozzle effect is alsowell shown in this view. It is also found that alternate adjacent barends may to advantage be provided with a pair of quadrant apertures 5,as shown in the second bar of Fig. 1, so as to utilize the space outsideof what would otherwise be the end apertures 6 of alternate bars.

Each pair of narrow apertures 6 comprises two substantially straightholes or jets also restricted at their upper ends. The nozzle-like shapeand the upward divergence of these apertures is well shown in the middlebar of Fig. l I

In order that the circle group holes 5 and the line-group holes 6 maycome in alternate alinement when the bars are assembled, the groupspacing is made alike on all of the bars and alternate'bars :begin withholes 5 and 5' respectively as shown in Fig. 1. This result may be hadby making the bars a'll alike, and each terminating at one end with aquadrant group of holes 5, and at the opposite end with a circlegroup ofholes 5, and then assembling the bars in alternate relative position, aswill readily be understood by reference to Fig. 1.

The bars are thickened vertically some what at their ends or hearingpoints 1, and as a result the casting is more massive here. The ribs 3and 4: terminate somewhat short of the bar ends, so as to leave a flateven bearing surface on the under side, as shown in Fig. 2.

In order that the grate as a whole may readily be made substantially airtight, except for the holes 5 and 6, and in order to made due allowancefor expansion and 'shrinkage'at times, provision is made for deep ashpockets 7 between bars. For this purpose a slight rim or flange 8 iscast or otherwise provided on the outer side of the outer ribs 4adjacent to their lower edges and extending the whole length of thebars, the abutting flanges 8 on .adjacent bars constitutingcomplementary bottomparts of the pockets 7 Each pocket flange 8 followsthe 3, which like rib 4 is deepest at the center and turns upwardsharply near the ends as shown at 8 'on Fig. 2, from whence it extendshorizontally to the tip of the bar. lVhen the bars are assembled in thegrate they are preferably spaced slightly at the edges of the pocketflanges 8, so as to accommodate expansion, but not enough to permitashes to leak through appreciably. In use the pockets? soon becomepacked full of ashes and cinders and are practically air tight so thatthe draft is limited to the spe-' cial draft apertures 5 and 6. When theiVl-bars are thus assembled in the grate the adjacent flanges 3 ofadjoining bars constituge complementary parts of composite grate n s.

The draft air is heated mainly as it passes aipward at comparatively lowspeed through v 110 downwardly convex curved edge of the rib the longnarrow channels or grooves 9 between the ribs 3 and 4, and receives itsfinal high degree temperature as it rushes out through the narrow jets 5and 6. From these jets the hot air blast is driven obliquely upward wellinto the mass of burning fuel so that combustion is hastened and a moreintimate mixture of air with the combustible gases passing to thecombustion chamber occurs.

Although but one specific embodiment of this invention has been hereinshown and described, it will be understood that numerous details of theconstruction shown may be altered or omitted without departing from thespirit of this invention as defined by the following claims.

I claim:

1. In a grate adapted for preheating the air and efiicientlydistributing same in connection with forced draft, a plurality ofapertured grate bars disposed closely together in draft-tight relation,the apertures in each bar being in the form of perforations disposed indefinite group arrangements, each bar having uniformly spacedalternating group forms, the adjacent bars having different group formsdisposed adjacently.

2. In a grate adapted for forced draft, a plurality of apertured gratebars disposed closely together in draft-tight relation, the apertures ineach bar being in the form of peculiarly shaped perforations disposed ingroup forms disposed adjacently,

definite group arrangements, each bar having uniformly spacedalternating group forms, the adjacent bars having different the holes insaid groups being disposed symmetrically about their respective groupaxes and inclined divergently toward the top.

3. In a grate, a plurality of g'ate bars each having a downwardly ribbedflat body part containing alternate groups of perforations, one seriesof said groups being ar ranged in pairs and the groups of the otherseries being arranged each in circular form, the circular groups in onebar being opposite the pair groups in the adjacent bars, and vice versa.

4:. A grate having draft apertures in distinct groups of circular andright-line form respectively, said groups being disposed alternately ineach of two directions at right angles to each other, said gratecomprising a series of downwardly ribbed bars in which the saidapertures are formed, said bars having medial ribs and deep lateralflanges which abut at their lower edges against corresponding flanges onadjacent bars and constitute complementary parts of composite grateribs, and the apertures of each group bein disposed symmetrically withrespect to said medial ribs.

Signed at Chicago this 28th day of April 1917.

ALLAN M. MASSER.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, I). G.

